Fishing overshot tool

ABSTRACT

A fishing tool gripper head including at least one moveable jaw of a set of jaws, a motivator including one or more of an SMA, SMP, or EAP material in operable communication with the at least one moveable jaw and a method for engaging a fish in a wellbore.

BACKGROUND OF THE INVENTION

In the hydrocarbon recovery industry stuck tools are known to all butthe very newest hands. Tools can become stuck in the downholeenvironment in more ways than one would be happy to recount and theyoccur often. For this reason “Fishing” has developed as an industry.Fishing tools are designed to be run in the hole to ultimately engagethe stuck tool (“fish”) and pull it out of the hole. Over the yearsfishing has been very successful in developing tools to accommodate mostevery iteration of a stuck tool. In most cases however, the range of aspecific tool with respect to the size fish it can engage is about plusor minus 1/16 inch. Due to the limited range of individual tools and theplethora of tool sizes that might and do become stuck, a great manyfishing tools must be stocked to ensure that a right sized tool isavailable to retrieve whatever is stuck in the well. Having such a largenumber of tools at the ready can be expensive if an operator intends tostock his own and requires a lot of storage space, or in the event thata fishing operator will be engaged to bring tools to remove the stucktool, can create undesirable delays. The art will therefore be receptiveto alternatives to traditional fishing tools.

SUMMARY

A fishing tool gripper head including at least one moveable jaw of a setof jaws, a motivator including one or more of an SMA, SMP, or EAPmaterial in operable communication with the at least one moveable jaw.

A method for engaging a fish in a wellbore including running a fishingtool with an adjustable gripper head and facilitating a thresholdcondition at the gripper head to cause a change in the dimension of thegripper head, the method further including engaging a fish.

BRIEF DESCRIPTION OF THE DRAWINGS

Referring now to the drawings wherein like elements are numbered alikein the several Figures:

FIG. 1 is a schematic side view of a wire wrapped gripping head asdisclosed herein;

FIG. 2 is a schematic end view of torsion spring wrapped embodiment;

FIGS. 3A and 3B are sequential views (unactuated and actuated,respectively) of another embodiment.

DETAILED DESCRIPTION OF THE INVENTION

A detailed description of one or more embodiments of the disclosedapparatus and method are presented herein by way of exemplification andnot limitation with reference to the Figures.

An adjustable gripper head 10 as referred to herein may have one or moreengagement jaws 12 that are movable radially inwardly or radiallyoutwardly or both depending upon the construction and intent of thefishing tool of which they will be a part. In all cases, at least one ofthe set of engagement jaws will be mobile. For purposes hereof, the termset includes one or more. This will be the case whether or not one ormore other of the segments (if more than one) are mobile. The mobilityof the segments in conjunction with a motivator 14 to cause movementthereof is discussed further hereunder with reference to the figures.

Referring to FIG. 1, a plurality of segments or jaws 12 are illustratedwith at least one of a shape memory alloy or polymer, or an electricallyactivated polymer wire 14 helically wrapped therearound. It is notedthat the material can also be combined with other materials and remainswithin the scope of this disclosure. Because each of the materials notedhas the capability of changing dimension upon a temperature change orupon the application of a voltage thereto, each can be configured to actas a motivator for the one or more mobile segments 12. In the particularembodiment illustrated in FIG. 1, the gripper head 10 comprises two jaws12 that are illustrated as diametrically opposed to one another. Thisarrangement could have merely two jaws or could have another number ofjaws that are positioned outside the plane of the cross sectionillustrated. Either or both of the illustrated jaws 12 can be configuredto be movable as desired. In either case, the spacing between the jaws12 is adjustable through actuation of the wire motivator 14 wrappedtherearound, the wire being fixedly located at both longitudinal endsthereof (or some other spaced apart locus for affixation not necessarilyat the end of the wire 14). As will be recognized, shape memory alloys,shape memory polymers and electrically activated polymers all can beconfigured to, under a temperature threshold or electrical inputthreshold, change their shape. One of the changes that is possible islength of the material in a wire form. This is the configurationemployed in the embodiment illustrated in FIG. 1. When a temperature towhich the motivator 14 is exposed or an electrical input to which themotivator 14 is exposed exceeds a selected value, the material willshorten axially of the wire material itself. This causes a shortening ofthe wire 14. Because the wire is affixed at its longitudinal ends or atleast at some spaced apart location therealong, the shortening of thewire 14 causes an effective radial load to be placed upon the jaws orsegments 12. This will cause the at least one mobile segment or jaw 12to move radially inwardly thereby reducing the distance between the jaws12. The reduction in distance makes the gripper head 10 more tolerant todifferent size fish. Rather than being restricted to a tolerance ofabout plus or minus 1/16 inch, the tolerance of the gripping head asdisclosed is about plus or minus ⅛ inch. Further, while the illustrationcontemplates an adjustability from a rest position to an actuatedposition that is smaller than the rest position, it will be understoodthat the capability of shape memory alloys, shape memory polymers andelectrically activated polymers or combinations including at least oneof the foregoing (hereinafter SMA, SMP and EAP) is not limited to ashortening of the material but rather can also be configured to lengthenthe material. Therefore it will be appreciated that the illustration ofFIG. 1 can be reversed such that the restring position is the smallestposition and the actuated position is a larger diametric position.

In a second embodiment, and referring to FIG. 2, a band 20 of SMA, SMP,EAP or combinations including at least one of the foregoing ispositioned around a set of jaws or segments 12 similar to that of theforegoing embodiment of FIG. 1. Each of the operational features or theFIG. 1 embodiment applies to the embodiment of FIG. 2. In thisembodiment, a greater actuation force is achievable due to the increasein amount of SMA, SMP, EAP or combinations including at least one of theforegoing employed. The greater force capability comes at the expense ofincreased material cost for manufacturing. Again, as in the embodimentof FIG. 1, the components may be reversed in operation to expand ratherthan contract the arrangement.

Referring to FIGS. 3A and 3B, a different configuration of is employedto directly act upon one of the jaws 12 at a time, one being shown. Itwill be understood that one or more jaws in a set of jaws may beconfigured as illustrated in FIG. 3. In this embodiment the shape changecapability of SMA, SMP, EAP or combinations including at least one ofthe foregoing is being utilized differently than in the previouslydisclosed embodiments in that the shape change directly rather than alength change caused by the shape change is employed. A review of thedifference between FIGS. 3A and 3B clearly illustrated the directdisplacing action of the embodiment. As in the foregoing embodiments,the components may be easily reversed to cause the jaws 12 to moveradially inwardly or radially outwardly depending upon the actiondesired in the tool.

While preferred embodiments have been shown and described, modificationsand substitutions may be made thereto without departing from the spiritand scope of the invention. Accordingly, it is to be understood that thepresent invention has been described by way of illustrations and notlimitation.

1. A fishing tool gripper head comprising: at least one movable jaw of aset of jaws; a motivator including one or more of an SMA, SMP or EAPmaterial in operable communication with the at least one movable jaw. 2.The gripper head as claimed in claim 1 wherein the motivator is a wire.3. The gripper head as claimed in claim 1 wherein the wire is helicallywrapped around the set of jaws.
 4. The gripper head as claimed in claim1 wherein the motivator is a band.
 5. The gripper head as claimed inclaim 1 wherein the band is wrapped around the set of jaws.
 6. Thegripper head as claimed in claim 1 wherein the motivator is a directlydisplacing motivator.
 7. The gripper head as claimed in claim 1 whereinjaws other than the at least one movable jaw of the set of jaws areimmobile.
 8. A method for engaging a fish in a wellbore comprising:running a fishing tool with an adjustable gripper head; facilitating athreshold condition at the gripper head to cause a change in thedimension of the gripper head; engaging a fish.
 9. The method as claimedin claim 8 wherein the threshold condition is at least one oftemperature and electrical input.
 10. The method as claimed in claim 8further comprising pulling the fish out of the wellbore.